The related art regarding a control system for the above-mentioned type of working vehicle is disclosed in JP,B 8-6613 and Japanese Patent No. 2968558.
The related art disclosed in JP,B 8-6613 is intended for a system in which two kinds of engine output characteristics, i.e., an engine output characteristic adapted for work and an engine output characteristic adapted for traveling, are prepared and the engine output characteristics are switched over from one to the other for control of an engine output in use depending on whether a vehicle is in a working state or a traveling state. When the vehicle is in the traveling state and a torque converter speed ratio is small (low speed), the amount of injected fuel is controlled so that a transmission torque will not exceed the torque in the working state, thereby preventing generation of an excessive torque applied to a torque converter.
According to the related art disclosed in Japanese Patent No. 2968558, when the sum of respective loads of a travel driving unit and an actuator is smaller than an engine output torque, a pump absorption torque is increased to ensure work performance. Also, when the load sum is larger than the engine output torque, the pump absorption torque is reduced to ensure a large travel torque for maintaining a large tractive force.
Patent Reference 1: JP,B 8-6613
Patent Reference 2: Japanese Patent No. 2968558